1. Field of the Invention
The present invention relates to an air bag system which is arranged in the instrument panel of a vehicle.
2. Related Art
In the prior art, the air bag of an air bag system arranged in front of the navigator's or passenger's seat is required to be inflated to a certain depth or extent. This is because the distance between the passenger and the instrument panel is relatively large with the air bag arranged in the instrument panel. As a result, the air bag per se is formed into a bag shape having a deepened square prism (as disclosed in Japanese Utility Model Publication No. 3229/1977 or Japanese Patent Laid-Open 136942/1991).
This air bag is manufactured by three-dimensionally sewing four base cloths, one for each of the four side walls, one top wall and one bottom wall of the generally square prism. These four include a first base cloth for the top wall and two side walls; two base cloths for the remaining side walls; and a fourth base cloth for the bottom wall. This complicates the sewing operation of the air bag.
Where three base cloths are used, a first will be for the top wall, the bottom wall and two side walls, with two base cloths being used for the remaining two side walls. Here, it is necessary to sew the three base cloths three-dimensionally. This sewing operation is also troublesome.
In order to eliminate such sewing problems, it is conceivable, as in a driver's air bag arranged in the steering wheel, to sew together two circular base cloths along their peripheral edges. In this case, however, the depth size is insufficient because two planar base cloths are used. This causes an inflated air bag to interfere with the windshield arranged at an inclination above the instrument panel. Accordingly, it is difficult to obtain an air bag configuration that will be simple to construct yet exhibit sufficient depth, toward the passenger, to be fully functional, even if the driver's air bag of the prior art is used as it is.